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onsemi 1SMB45AT3
- Part No.:
- 1SMB45AT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
1SMB45AT3.pdf
- Description:
- TVS DIODE 45VWM 72.7VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:5,838
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Product details
Overview
1SMB45AT3 from ON Semiconductor is a unidirectional 600 W transient voltage suppressor (TVS) diode designed for parallel overvoltage protection of DC power rails and signal lines. It features a 45 V working peak reverse voltage (VRWM), 55.3 V maximum clamping voltage at 8.3 A peak pulse current (VC @ IPP), and <1.0 ns response time. It is used in automotive power supply inputs, industrial PLC I/O modules, and telecom line interface circuits to absorb ESD and lightning-induced surges.
For engineers reviewing the 1SMB45AT3 datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM ≥ system operating voltage, VC margin relative to protected IC absolute maximum ratings, surge current capability under 10/1000 µs waveform, and UL 497B recognition for isolated loop protection compliance.
Technical Context
The 1SMB45AT3 operates as a Zener-based avalanche clamp: under normal bias it presents <5.0 µA leakage above VRWM = 45 V; during transients exceeding VBR = 50.0–52.65 V (measured at IT = 1.0 mA), it avalanches into low-impedance conduction to limit voltage to ≤72.7 V at IPP = 8.3 A. Its Surmetic SMB package enables thermal dissipation up to 3.0 W at TL = 75°C with 40 °C/W junction-to-lead resistance.
It is rated for 600 W non-repetitive peak power per 1 ms pulse (10/1000 µs waveform), supports 100 A forward surge current (IFSM), and achieves Class 3 ESD robustness (>16 kV HBM). Its 385 pF junction capacitance at 0 V bias makes it suitable for DC and low-frequency AC protection but not high-speed data lines.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 45 V - Maximum continuous reverse operating voltage before clamping begins; must exceed circuit's DC or peak AC voltage. |
| VBR @ IT=1mA | 50.0–52.65 V - Breakdown onset range; defines minimum clamping threshold under standardized test conditions. |
| VC @ IPP=8.3A | 72.7 V - Maximum clamped voltage during 10/1000 µs surge; determines worst-case stress on downstream components. |
| PPK | 600 W - Peak transient power handling for 1 ms pulse; defines single-event surge energy absorption capacity. |
| IR @ VRWM | 5.0 µA - Reverse leakage at rated working voltage; ensures minimal standby power loss and signal integrity. |
| Junction Capacitance | 385 pF @ 0 V - Capacitive loading on protected node; limits use to ≤1 MHz signal paths or DC rails. |
| Response Time | <1.0 ns - Time from transient onset to clamping initiation; enables protection of fast-rising ESD and switching spikes. |
| UL Recognition | UL 497B QVGQ2 - Certified for isolated loop circuit protection; validates reliability in safety-critical telecom and industrial interfaces. |
Pinout & Package
1SMB45AT3 is housed in an SMB (DO-214AA) surface-mount plastic package (Case 403A), featuring a cathode band marking and modified L-bend leads for enhanced solder joint reliability. The device has two terminals: anode and cathode, with polarity indicated by a visible band on the cathode end.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry point during forward conduction; connected to lower-potential side of protected circuit. | Used only during fault conditions (e.g., reverse polarity events); normally reverse-biased in TVS operation. |
| Cathode | Current exit point during reverse avalanche clamping; connected to higher-potential side (e.g., VBUS or signal line). | Primary terminal for surge current diversion; must be routed with minimal inductance to ground or return path. |
Key Features
| Feature | Design Value |
|---|---|
| 600 W peak pulse power | Enables robust protection against IEC 61000-4-5 Level 4 (4 kV/2 Ω) surges without derating in compact SMB footprint. |
| UL 497B recognition | Validates suitability for certified isolated loop protection in industrial process controllers and telecom interface cards. |
| <1.0 ns response time | Minimizes voltage overshoot during sub-nanosecond ESD events (IEC 61000-4-2), reducing risk of latch-up or gate oxide damage. |
| Pb-free (G suffix) packaging | Complies with RoHS Directive 2011/65/EU and JEDEC J-STD-020 reflow profile for lead-free assembly. |
| Low zener impedance | Ensures stable clamping voltage across varying surge currents-critical for protecting fixed-threshold ICs like RS-485 transceivers. |
Applications
| Automotive Power Input Protection | Industrial PLC Digital I/O Protection |
|---|---|
Use Scenario: 12 V battery-fed ECUs exposed to load dump (ISO 7637-2 Pulse 5a, up to 60 V/100 ms) and jump-start transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between VBAT and GND to clamp overvoltage before it reaches DC-DC converter input. Use Value: 72.7 V clamping ceiling prevents damage to 40 V-rated input MOSFETs and maintains system uptime during harsh vehicle electrical events. |
Use Scenario: 24 V digital input modules receiving signals from field sensors in factory automation environments. IC Role / Device Role / Timing Role: Parallel-connected TVS on each input channel to shunt induced surges from relay coil back-EMF or nearby welding equipment. Use Value: 5.0 µA leakage preserves high-impedance sensing accuracy; 600 W rating handles repetitive 10/1000 µs transients common in industrial noise environments. |
| Telecom Line Interface Protection | Medical Equipment Power Rail Protection |
Use Scenario: T1/E1 line interface cards in central office equipment subjected to lightning-induced longitudinal surges. IC Role / Device Role / Timing Role: Primary protection device in series with isolation transformer secondary, referenced to telecom ground. Use Value: UL 497B certification confirms compliance with safety requirements for primary protector classification in telecom infrastructure. |
Use Scenario: Auxiliary 5 V/12 V power rails in diagnostic imaging systems requiring immunity to ESD and conducted emissions per IEC 60601-1-2. IC Role / Device Role / Timing Role: Secondary-level TVS on board-level DC distribution nets to prevent transient coupling into analog front-end circuitry. Use Value: Sub-1 ns response ensures clamping occurs before sensitive ADC reference or op-amp inputs experience overvoltage beyond absolute maximum ratings. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ45A | Same VRWM (45 V), identical SMB package, but rated for 600 W with tighter VC spec (70.1 V @ 8.3 A vs. 72.7 V). | Preferred where lower clamping voltage margin is required for 50 V-tolerant ICs; slightly higher cost due to tighter binning. | Select SMBJ45A when VC headroom below protected IC's absolute max rating is less than 2.7 V. |
| 1.5SMC47A | Higher power rating (1500 W), same VRWM (45 V), but larger SMC (DO-214AB) package (7.11 × 6.22 mm vs. SMB's 4.32 × 2.62 mm). | Suitable for high-energy surge environments (e.g., outdoor base stations), but requires PCB area increase and layout revision. | Choose 1.5SMC47A only if system-level testing shows 600 W insufficient for worst-case lightning surge profiles. |
Compared with SMBJ45A and 1.5SMC47A, the 1SMB45AT3 offers optimal balance of compact SMB footprint, UL 497B certification, and proven 600 W surge handling-making it ideal for space-constrained industrial and automotive control modules where regulatory compliance and board area are critical.
Availability
1SMB45AT3 is available at Aetrix Electronics and suitable for automotive infotainment power supplies, industrial PLC I/O modules, and telecom line interface cards requiring stable component supply across multi-year production cycles.
Supply support for 1SMB45AT3 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
ON Semiconductor (now onsemi) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensor, and connectivity solutions for automotive, industrial, and cloud power applications.
The 1SMB45AT3 belongs to the SMB series of unidirectional TVS diodes engineered specifically for high-reliability overvoltage protection in harsh electromagnetic environments-emphasizing low clamping, fast response, and regulatory compliance for mission-critical systems.
FAQ
What is the maximum clamping voltage of the 1SMB45AT3 under standard surge conditions?
The 1SMB45AT3 exhibits a maximum clamping voltage (VC) of 72.7 V when subjected to an 8.3 A peak pulse current (IPP) with a 10/1000 µs waveform. This value is measured per industry-standard transient test conditions and defines the upper voltage limit imposed on protected circuitry during surge events. Designers must ensure this clamping level remains below the absolute maximum voltage rating of downstream components. The 1SMB45AT3 datasheet specifies this parameter on page 3 under Electrical Characteristics.
Does the 1SMB45AT3 meet UL safety standards for industrial applications?
Yes, the 1SMB45AT3 carries UL 497B recognition (File #E210057, category QVGQ2) for isolated loop circuit protection. This certification confirms successful completion of multiple safety tests including strike voltage breakdown, endurance conditioning, dielectric withstand, and discharge performance-making it suitable for use in certified industrial control panels and telecom infrastructure. The 1SMB45AT3 is explicitly listed in the UL recognition documentation for the entire SMB series.
Can the 1SMB45AT3 be used in bidirectional signal line protection?
No, the 1SMB45AT3 is a unidirectional TVS diode and is not suitable for bidirectional signal line protection such as RS-485 or CAN bus. Its design clamps only in reverse bias; forward conduction occurs at ~0.8 V, offering no surge suppression in the forward direction. For bidirectional protection, ON Semiconductor offers the 1SMB45CAT3 ('C' suffix), which is the complementary bidirectional variant with symmetrical ±45 V standoff capability. Always verify polarity configuration before selecting the 1SMB45AT3.
What is the thermal resistance and power derating behavior of the 1SMB45AT3?
The 1SMB45AT3 has a junction-to-lead thermal resistance (RJL) of 40 °C/W and a junction-to-ambient resistance (RJA) of 226 °C/W on a standard FR-4 board. Its DC power dissipation is rated at 3.0 W at TL = 75°C, derating linearly above that temperature at 25 mW/°C. At TA = 25°C, PD is 0.55 W with 4.4 mW/°C derating. These values are defined in the Maximum Ratings table (page 2) of the 1SMB5.0AT3 Series datasheet and must be applied in thermal design calculations for sustained surge duty cycles.
How does the 1SMB45AT3 compare to the 1SMB45AT3G variant?
The 1SMB45AT3 and 1SMB45AT3G share identical electrical specifications, package dimensions, and performance characteristics. The 'G' suffix denotes Pb-free (RoHS-compliant) construction with matte tin lead finish, while the base 1SMB45AT3 may use leaded terminations depending on manufacturing lot. Both variants are functionally interchangeable in designs compliant with either RoHS or legacy leaded assembly processes. ON Semiconductor documents this equivalence in the Ordering Information section (page 1) of the datasheet.
1SMB45AT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-214AA, SMB
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 45V
- Voltage - Breakdown (Min):
- 50V
- Voltage - Clamping (Max) @ Ipp:
- 72.7V
- Current - Peak Pulse (10/1000µs):
- 8.3A
- Power - Peak Pulse:
- 600W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- 385pF @ 1MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMB
1SMB45AT3 FAQ
1.How can I place an order for 1SMB45AT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMB45AT3 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for 1SMB45AT3 reliable?
The price and inventory of 1SMB45AT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMB45AT3 is usually 5 days.
3.What payment methods are accepted for 1SMB45AT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMB45AT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMB45AT3?
1SMB45AT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMB45AT3 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for 1SMB45AT3?
For technical support, including 1SMB45AT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMB45AT3 requirements.
6.How does Aetrix verify that 1SMB45AT3 is sourced from the original manufacturer or authorized distributors?
All 1SMB45AT3 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that 1SMB45AT3 meets industry standards.
7.What is the process for return or replacement of 1SMB45AT3?
All 1SMB45AT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMB45AT3, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The 1SMB45AT3 part is unused and in its original packaging.
Return procedure for 1SMB45AT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMB45AT3 Tags
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